1. Statement of the Technical Field
The inventive arrangements relate generally to methods and apparatus for tracking people and objects.
2. Description of the Related Art
Tracking of people and objects continues to become increasingly important in modern times, in large part due to increased levels of security that are often required to protect against terrorism and corporate espionage. In response, tracking systems have been developed for tracking people and objects, although many of these systems are very costly to implement, maintain and operate.
To address concerns about operational costs, passive electronic product code (EPC) radio frequency identification (RFID) tags have been developed. In contrast to conventional RFID tags which actively transmit identification data, the passive RFID tags do not require an independent power source, but instead operate using power received from compatible RFID scanners. Accordingly, systems using the passive EPC RFID tags are less expensive to operate as compared to other types of RFID systems. However, the range at which the passive RFID tags can be scanned is much smaller than the scanning range of active RFID tags. Thus, when passive RFID tags are used, RFID scanners must be deployed in a manner that compensates for the reduced scanning range.
Notwithstanding the operational cost savings that can be realized using passive RFID tags, the implementation and maintenance costs of such systems still make the technology cost prohibitive for use in many venues, for example for use in commercial travel centers. In particular, cable installation and the installation of specialized RFID system components are expensive.
Further, it is also very expensive to re-wire facilities and move the specialized RFID system components when building modifications are made or operational requirements change. Moreover, the time necessary to re-wire the facilities and move the system components also is unacceptable in many instances. This is especially significant when threats are constantly changing and rapid deployment and configuration is critical to the overall effectiveness of the system.
Reliability is yet another issue of concern with existing RFID tracking systems. Such systems typically utilize a central server or controller based architecture. If the central server or controller fails or goes off-line, the entire RFID tracking system becomes inoperable; this is unacceptable in certain venues. To reduce the risk of a server or controller going off-line, such system components are usually located in an area having special security provisions, again increasing the cost associated with using such systems.
A small number of patents have issued in recent years which are useful for understanding the prior art. For example, U.S. Pat. No. 6,608,551 to Anderson, et al. (“Anderson”) discloses a system for tracking RFID devices using RFID tags in lieu of special purpose radios. The system uses active tags that radiate energy to a series of interrogators connected to a computer. The computer processes data from the interrogators and determines the location of the RFID tag within its cellular array of readers. Anderson relies on the user of active RFID tags.
U.S. Pat. No. 6,246,882 to Lachance (“Lachance”) discloses a system using a cellular network to provide a network for communicating RFID information to a central database. The location of the cells is known and can be correlated to a geographic area.
U.S. Pat. No. 6,509,829 to Tuttle (“Tuttle”) discloses a system for locating an individual in a facility. The system uses a portable wireless transponder device borne by the individual; an interrogator; and a plurality of antennas distributed in the facility. The interrogator repeatedly transmits a wireless command to the portable wireless transponder device using alternating antennas. In response, the portable wireless transponder device transmits data identifying the portable wireless transponder device if it is within communications range of the antenna sending the command. The individual in the facility is therefore locatable by determining with which antenna the interrogator was able to establish communications with the portable wireless transponder device. However, Tuttle depends on a fixed network.
U.S. Pat. No. 6,014,628 to Kovarik (“Kovarik”) discloses a system for tracking objects through a collection of distributed nodes that are networked together. The system addresses the underlying tracking process utilizing predictive methods based on temporal relationships integrated with a workflow representation that is encapsulated on the object being tracked. Kovarik does not, however, address RFID or any other means of externally identifying objects being tracked in a physical environment.